One Note with more to follow with pictures.The old repeaters come with a measuring scale printed on the arms.
The new repeaters don't offer a printed scale.
If you like to extend the capacity from 26" to 48" there is a charge for that.
If you have the repeaters with the smart clamping system,
keep the smart clamping system. You can use it without the repeaters.
If your square works fine without going off (due to heavy use or bumping)
bst to keep it and save the shipping cost.
If you can do the modifications, ( we will show you how) better to get the washers and knobs ( free shipping ) and avoid the hassle.

SRK. If you know how to adjust the SRK slide, better to keep the old one.
The best way is to make the adjustments and secure the parts with with few screws. ( Good to learn how to drill and tap)
The new SRK is made to be easily adjustable.

B-300. Nothing to return.
You need the new aluminum bars and special screws with nylon washers.
The first production run was done using connectors or 1/2"x 3/8" aluminum bars.
The Bridge works fine but the new aluminum bars and the screws/nylon washers
are going to prevent any future problems.